1. Field of the Invention
The present invention relates to monitoring methods for telecommunication transmissions, more particularly to a method and apparatus for automatically marking a mobile subscriber or terminal for monitoring a telephone communication session or transmission associated therewith.
2. Description of the Prior Art
Law Enforcement Agencies (LEAs) may sometimes require a cellular operator, i.e. the company operating a cellular telecommunication network, to intercept communications of cellular subscribers, and then forward both the content of the communication and the call identifying information to them. Such an action is typically performed when the LEAs obtain a court order for monitoring a particular subscriber line. Once the court approval is obtained, the LEA requests the cellular operator to monitor the communications of the subscriber and furnishes the subscriber""s personal identification thereto for the purpose of monitoring. It is the responsibility of the cellular operator, then, to perform the monitoring, i.e. gather communication data related to the monitored subscriber, and to forward it to the LEA. The forwarding of this information may either be performed at spaced intervals or, as it is more and more likely to happen, in quasi real-time.
Various methods exist for marking or otherwise identifying a telephone subscriber, such as a cellular subscriber, for monitoring the communications sessions or transmissions associated therewith. In some cases, the LEAs may want to monitor the subscriber, and in that case the cellular operator may use the Mobile Identification Number (MIN), the Mobile Directory Number (MDN), or the International Mobile Subscriber Identity (IMSI) for tracing communications involving that subscriber. When such techniques are used, it is the subscriber (through the subscriber profile that may be stored in a SIMM card within the mobile phone) who is monitored. In other cases, the LEAs may want to monitor only communications involving a particular equipment, such as a particular mobile station, and in that case the cellular operator may use the Electronic Serial Number (ESN), or the International Mobile Equipment Identity (IMEI), which are unique to each mobile station.
Current techniques of monitoring a marked subscriber have considerable shortcomings and deficiencies. Typically, monitoring a subscriber means that calls emanating from or received by only the marked subscriber are monitored. In other words, communications relating to the subscribers who either called the marked subscriber or were called by the marked subscriber are not monitored at all. It can be readily appreciated that by not monitoring additional subscribers who have been participants in communications with the marked subscriber, chances for the LEA to gather potentially incriminating information related to the monitoring subscriber are greatly reduced. Indeed, it can be surmised that the monitored subscribers pay attention to the content of their communications, and therefore avoid divulging or transmitting potentially incriminating information from their own mobile terminal. Instead, such incriminating information may be found in additional communications emanating from the participating subscribers subsequently talk to other subscribers.
Therefore, it would be advantageous to have a system and method that allows systematic and automatic supervision of communications emanating either from subscribers once called by the monitored subscriber, or from subscribers who once called the monitored subscriber. It would be of further advantage if such a system and method could be implemented in both the cellular telecommunications network and the Public Switched Telephone Network (PSTN), either cumulatively or involving separate portions thereof.
It is therefore one broad object of this invention to provide a method and apparatus for automatically marking for monitoring at least one or more un-marked participants in a telephone communication session or transmission with a subscriber marked for monitoring by the LEA.
The present invention overcomes the disadvantages of the prior art methods for monitoring a subscriber, by allowing automatic monitoring of subscribers who have been contacted, or who have contacted the monitored subscriber. In this manner, the chances for the LEAs for finding potentially incriminating information relating to the monitor subscribers are greatly improved, since not only the communications of the initially monitored subscriber are monitored, but also those of the other subscribers contacted by the initially monitored subscriber, which may not involve the initially monitored subscriber.
In one aspect of the invention, when a subscriber is marked for automatic monitoring (the marking uses preferably one of the identification data types explained in the Background section), a timer associated with each one of the marked subscribers is started, so that the monitoring may be performed, preferably, only for a selected period of time, thus avoiding overloading the network.
In another aspect of the invention, a marking level associated with the subscriber to be monitored is detected prior to marking the subscriber. Preferably, the subscriber is marked for monitoring only when the detected marking level associated with the subscriber satisfies a pre-defined condition.
In yet another aspect, only a limited number of communication sessions or transmissions are preferably monitored for a newly marked subscriber. Once a predetermined threshold level associated with the number of communication sessions is reached, the subscriber is then un-marked so that the subscriber would no longer be monitored.
In one embodiment, the present invention is drawn to a method for automatically marking for monitoring at least one telephone subscriber participating in a communication transmission in a telephone network. First, the communication transmission is set up in a telephone network between at least two telephone subscribers such that the transmission emanates from a first subscriber and is directed to the other. If at least one of the subscribers participating in the communication transmission is detected to be marked for monitoring, the method automatically marks the remaining subscribers participating in the communication transmission for subsequent monitoring.
In another embodiment, the present invention is directed to a telephone network system comprising communication switching means for setting up a communication session between at least two subscribers. The telephone network system is also provided with intercepting means for intercepting the content, identifying information, or both, associated with the communication session. Also provided is monitoring marking means which detects the presence of a monitored subscriber among the subscribers participating in the communication session. When the monitoring marking means detects that a monitored subscriber is present among the participating subscribers, the remaining subscribers are automatically marks for monitoring also.